Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935042AbZAOW7S (ORCPT ); Thu, 15 Jan 2009 17:59:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761915AbZAOWpM (ORCPT ); Thu, 15 Jan 2009 17:45:12 -0500 Received: from smtp-out.google.com ([216.239.45.13]:10037 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758495AbZAOWpH (ORCPT ); Thu, 15 Jan 2009 17:45:07 -0500 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=mime-version:in-reply-to:references:date:message-id:subject:from:to: cc:content-type:content-transfer-encoding: x-gmailtapped-by:x-gmailtapped; b=hkXghJx+f+m1VRJglBjbpeekO5enx5mEk2FXYg4nVJFfD90K8LaphsEfgNaOOpjnC 7hbNPsyDhRT59VbdiWfbw== MIME-Version: 1.0 In-Reply-To: <1232046039.5966.54.camel@localhost.localdomain> References: <200901051952.58029.bzolnier@gmail.com> <20090106073515.GY32491@kernel.dk> <4964866D.8010503@msgid.tls.msk.ru> <1231342473.3282.19.camel@localhost.localdomain> <496ECBA0.60209@gmail.com> <87f94c370901150707h10506e99reaa40c23e32ab18c@mail.gmail.com> <1232035561.5966.48.camel@localhost.localdomain> <1232046039.5966.54.camel@localhost.localdomain> Date: Thu, 15 Jan 2009 14:45:01 -0800 Message-ID: Subject: Re: [PATCH] block: export SSD/non-rotational queue flag through sysfs From: Grant Grundler To: James Bottomley Cc: Jens Axboe , Greg Freemyer , Tejun Heo , Michael Tokarev , Kay Sievers , Bartlomiej Zolnierkiewicz , linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org, Alan Cox Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-GMailtapped-By: 172.25.146.78 X-GMailtapped: grundler Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1545 Lines: 38 On Thu, Jan 15, 2009 at 11:00 AM, James Bottomley wrote: ... >> Code can test for zero/nonzero or (preferably) more fine grained. >> e.g. "avgreadcost > 1ms" or "avgwritecost". I'm hoping this test >> can be abstracted into a macro. > > Um these really have to be things we can get out of the device at boot > time without effort (as in part of the data the device can give in a > single command). I'll be shot for increasing boot time so we can work > out these parameters ... No. The whole point is we should not care what it is at boot time. It should be based on recent history of what is going on. At boot time we read the partition table and we superblocks to mount file systems. That's fine to start with. So I don't see any need to add some synthetic test to establish initial values. The rest of the code should work regardless of what the values start out to be. This is true for the previous proposed patch too when user space has to decide what the right policy is. >> I'm hoping longterm, the values could be "self tuning" but don't know >> how that might work - e.g. 1 minute avg? 10 minute avg? Cost >> of collecting/maintaining the stats? Feels like a CONFIG option. > > CONFIG_SLOW_YOUR_BOOT? maybe CONFIG_AUTOTUNE_RWCOST. thanks, grant -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/